You are technically correct but being misleading. That is absolutely normal for browsers, and to my knowledge every single browser that has ever garnered more than 1% usage has done it exactly the same way. The parts that are not open source are the parts that would show exactly how to send whatever you wanted through the browser. If what you want is a 100% open source browser I wouldn't even consider using it, it would be insecure.
Freedom in our lifetime! - fiol.us